Time: 10:00a.m.Tuesday,August 30th
Growing environmental applications in water and gas separation pose new and interesting demands on both material and process design. At the UNESCO Centre for Membrane Science and Technology, our research spans new membrane processes and materials for water treatment and gas separation. For water and wastewater treatment, we have focused on process configurations and materials for separation of more recalcitrant streams such as hypersaline feeds, viscous, highly fouling biological effluents, and micropollutants.
From the material side, we have utilized surface functionalization of polymer membranes with segregating additives and inorganic coatings along with blending of 1D, 2D and 3D (framework) materials to enhance membrane performance. Recently, we have developed techniques to coat polymeric membranes with thin, nanostructured titania which can be easily functionalized to become low fouling, superhydrophobic/hydrophilic (Janus) interfaces, and substrates for enzyme immobilization for CO2 capture and micropollutant degradation. Our group has also focused on the synthesis of polymer nanocomposite membranes for gas separation via layer-by-layer coating and in-situ crystallization on porous polymer membrane surfaces. Addition of pre-synthesized ZIF-8, UiO66-COOH, and graphene oxide into PEO-PA block copolymers and subsequent of coating the selective layer onto a porous hollow fiber membrane surfaces can produce thin, nanocomposite membranes with significantly improved CO2 permeance while the CO2/N2 selectivity was relatively unchanged when compared with the pure polymer benchmark. This strategy has also been applied to enhance performance of dense film coatings of membrane distillation/pervaporation membranes for the treatment of hypersaline effluents.
Alternatively thin film ZIF-8 layer can be synthesized as a coherent ultrathin layer onto the polymer membrane surfaces using a facile, rapid, one-pot approach. These pure ZIF membranes were showed unusual flexibility as well as one of the highest H2 permeances for molecular sieving ZIF-8 membranes. This and other strategies to functionalize surfaces to more effectively grow MOFs on polymer substrates can be potentially exploited to produce high surface area devices for separation and sensing.